The invention refers to a process for the production of a pourable porous carrier material from at least one thermoplastic basic polymer with additives incorporated in the porous structure. The invention also refers to the use of the charged porous carrier material produced according to this process.
Polymers consist of molecule chains with numerous components which repeat themselves practically endlessly, which differ from low molecular compounds in relation to physical properties, for example in relation to their high tensile strength and elasticity.
Polymerized plastic masses have appropriate additives mixed in during industrial processes depending on the further processing and application. The basic polymers can thus be adapted to individual products and/or requirements.
Between basic polymers on one side and fluid or easily melting additives on the other, there is a great difference in viscosity which can lead to incompatibility. Usually therefore only low proportions of additives can be mixed into the basic polymers.
To avoid metering problems and to achieve a more homogeneous distribution, many plastic processors prefer a concentration of the relevant additives in the basic polymer. Thus a basic polymer or a mixture of basic polymers with one or several additives is heated, melted, mixed and transferred in a pourable form, for example in carrier materials charged with additives in granulate form. These are known as additive master batches.
For porous or microporous polymer structures, numerous production processes and various applications are known. Manufacturing examples are phase inversion, nuclear bombardment to incorporate microporous solid particles and sintering of small microporous particles.
U.S. Pat. No. 4,247,498 describes a process in which any synthetic thermoplastic polymers can be produced microporous. The polymers are heated in a compatible fluid as long and as far as necessary to form a homogeneous solution. This is brought into the required mold in which it is cooled until a thermodynamically unbalanced fluid/fluid phase separation occurs. Thus without the effect of mixing or other shear forces, a solid is produced which can be handled without physical degradation. Finally, at least one essential part of the fluid is removed from the resulting solid to form the required microporous polymer. A narrow spread of pore sizes, as measured by mercury intrusion porosimetry, is of essential importance and is expressed analytically with the sharpness function "S". By application of U.S. Pat. No. 4,247,498, polymers with spherical pores are produced which contain a functional active fluid such as polymer additives. The charged microporous polymers behave as solids and can be processed as such. To charge the microporous polymers, any organic fluid can be used which does not dissolve the polymer and which is compatible with this. The functional active fluid can be incorporated by absorption, exchange processes, infusion processes or similar known processes, also with the use of an intermediate product.